One Piece and DBZ being in their own category? They're both too generic and shounen-like to be called unique.
Both Detroit Metal City and Tengen Toppa Gurren Lagann didn't feel like anime to me. They felt more like american cartoons and animated comedies (like Metalocalypse <_<) to me.

I feel that Aria is just one of the few anime that stand out a lot...it's just so peaceful and Sketchbook too.
There's just this something about it that makes your heart just be like...chill or seomthing like that.
Most anime I watch...are just like...I fangirl over it, but this one, is where I like...worship it not fangirl it.

Geez you ask a simple question and people misconstrue it as you're being an ignorant asshole. Hmph! If you have something mean to say then don't say it.

They're angry because of 'animes that don't feel like anime.' In fact, 'those' are the sort of animes I often watch (and end up liking).

Examples:

-Legend of the Galactic Heroes
-Armored Trooper VOTOMS
-And, for some reason, Space Warrior Baldios, despite the fact that it's almost typical super robot.
-Dragon's Heaven (Don't be fooled by the name, the setting is full of robots)
-Hell, maybe even most of the grimdark shit Tomino made.

Hmm.... Windy Tales, maybe?? It has this great, serene feeling to it you don't get from most anime. It doesn't aim too high or try to out do itself, or mess around with pointless drama or saving the world or anything like that. It's basically about three normal, every-day girls who just happen to have the power to control the wind. It doesn't try to make things overly unusual or overly "Teehee!! I'm a normal girl!!". Because of that, you can really relate to the characters and their problems, and it feels.... Well, "realistic" isn't quite the right word for it, but it would be really realistic if girls who know how to manipulate the wind was realistic. Even so, it's never boring. It's really relaxing, though. You'd have to see it to really understand. Also, the characters already have established close friends and likes and dislikes, so it's not like their lives began the day the adventure started and they just kind of existed and did nothing much besides until then. The art's really unique and amazing, too, though it might not fit some people's style.

That's about it. For me, stuff that's MORE anime-like is usually better than LESS anime-like, so I'm not really sure. The Violinist of Hamelin, maybe?? But that's more like it's so stupid and low-budget that it doesn't meet my standards for anime, but it's so much fun to watch and to laugh at that you can't NOT watch it once you've started. The fact that the main character's clothes and hat can be destroyed or lost in almost every episode and they seem to just magically regenerate somehow is another thing that constantly cracks me up, as well as the positively fantabulous attack names ("JESUS SLASH!!!!!!!!!") and how it's so low-budget that there seem to be more freeze frames than actual animation. (Why is it that they never bother to animate the action scenes, but they can afford to animate the queen's eyebrow twitching, a random tidal wave, and people's mouths moving when we can't hear what they're saying??) It takes itself really seriously, too, which is even more hilarious. The characters are constantly getting these random mood swings, also, and somehow one character (who wears this weird football player/train conductor parody outfit with massive shoulder spikes) can carry a mini grand piano on his back and not either damage it, lose it, or collapse in exhaustion from carrying it all the time and the main character (the one whose clothes regenerate) has this massive violin that looks like a cello or something that he carries around everywhere. He also gets depressed because a horn randomly pops out of his head and can throw his weird hat like a Frisbee. The music is ridiculous, too (the first OP is this one that starts out normally enough, but turns into this weird techno-rock-pop-thing and has the really unfortunate English ending line "MA MA MAGICAL LALALALA LABYRINTH", while the second is this freaky Japanese opera thing with the ending line "DESTINAAAAAAAAAAAAAATION!!!!! DESTINAAAAAAAAAAAAAAAAAAAAAAATION STIIIIIIIIIIIIIIIILLLLL SOOO FAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARRRRR!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"). In all, it's a colossal train-wreck of an anime that's so horrible you really can't not watch it.

I can't say I agree with feeling like DBZ and such feel like they're in their own category, because growing up, Dragonball Z was THE anime. Everything that was aired afterwards was compared to it. But I guess since then, anime has developed it's own feel to it in the West. But I've yet to see an anime that never felt like one to me.